Managing green water: the impacts of land use change on water flows

摘要

Most of us recall learning in school that precipitation falling to Earth either runs off into rivers and recharges groundwater aquifers as blue water, or is subject to evaporation and transpiration -green water. In practice, in most societies only surface and ground-waters are subject to deliberate management, whereas the water consumed through land use processes is rarely measured, allocated or regulated. In most societies there has been an assumption that green water consumption is not significant enough to regulate. However, the growing demand for water, increasing water scarcity in many parts of the world, changing hydrology due to climate change -including the likelihood of more frequent floods and droughts -make active management of green water increasingly important to maintain essential services for people and nature. A number of governments are adopting policies to measure, regulate and manage green water, including Australia, South Africa and the United Kingdom.